This invention relates to the field of aircraft energy supply apparatus of both the auxiliary and emergency supply types.
A need for non-propulsion engine associated moderate quantities of electrical and other forms of energy in an aircraft has been recognized since the early days of aviation. Somewhat later in time, many World War II aircraft, especially the multi engine aircraft of this era, were provided with a small gasoline engine driven direct current generator which could supply electrical energy for starting of the propulsion engines, battery charging, and even a limited degree of communications and flight systems energization.
In the field of modern commercial airline equipment this supplying of auxiliary energy has evolved into many aircraft being self sufficient for indefinite periods when located on the ground, that is, these aircraft include apparatus providing engine starting, ground use air conditioning, communications, control, and illumination energy without the use of tether connections to permanent or portable external equipment. This same apparatus is also often made capable of supporting flight systems operation and emergency engine restarting sequences while the aircraft is in flight.
In this more modern equipment, the earlier-used single cylinder gasoline engine driven DC generator has evolved into a light-weight turbine driven apparatus that is capable of providing not only direct current electrical energy, but also multiple phased alternating current electrical energy, hydraulic pressure, compressed air and other energy forms to its host aircraft. In this modern embodiment the auxiliary power unit (APU) of earlier usage has evolved into an integrated power unit (IPU) which provides not only the energy needs for normal ground experience with the aircraft, but also is capable of emergency and safety use in the air as well.
The patent art includes a number of documents which are of general background interest with respect to the present invention. Included in these patents are U.S. Pat. No. 2,223,703 issued to H. C. A. Potez, patent which is concerned with an auxiliary service plant for an aircraft and in which either of two aircraft engines can be used to drive a bank of auxiliary load devices such as hydraulic pumps and generators. Since the Potez apparatus is not concerned with a high altitude and low altitude capable power unit, a ready distinction between the present invention and the Potez apparatus is apparent.
The patent art also includes U.S. Pat. No. 3,591,843 issued to one Helment Friedrich and concerned with an apparatus for starting one or several aircraft engines and for driving associated auxiliary equipment. Overrunning clutches and the like provide for driving the Frederich auxiliary equipment from the higher speed running of the multiple engines and selective cross coupling between these engines permits starting one engine from the other. Since the Friedrich apparatus is also not concerned with a high altitude and low altitude operable power unit, a ready distinction between the present invention and the disclosure of Friedrich is apparent.
The Patent art also includes a number of patents relating to magnetically operable couplings for axially aligned rotating shafts. Included in these patents are U.S. Pat. No. 4,446,392 issued to R. L. Jaeschke; U.S. Pat. No. 4,808,869 issued to N. L. Koop and U.S. Pat. No. 5,036,368 issued to Hroaki Nakamura. Since none of these coupling arrangements is concerned with a high altitude and low altitude operable aircraft power unit, the apparatus disclosed therein, although possibly useful in the present invention power unit, is not in itself significant with respect to the overall thrust of applicant's invention.
The art of general background interest with respect to the present invention also includes a Society of Automotive Engineers Inc. publication from the National Aeronautics and Space Engineering and Manufacturing meeting held at Los Angeles Calif., Oct. 4, 1965 to Oct. 8, 1965, an article titled "Integrated Secondary Power Systems" and identified with the SAE number 650828. This article was authored by Palmer R. Wood and William R. Spragins of the Air Research Manufacturing Division of the Garret Corporation and describes a number of accessory drive systems along with the advantages and disadvantages of each. Since the Wood and Spragins article is also not concerned with a high altitude and low altitude operating integrated power system a ready distinction with the present invention is apparent.